[PATCH v4 15/45] powerpc/mm: Allocate static page tables for fixmap

[Christophe Leroy]

Allocate static page tables for the fixmap area. This allows
setting mappings through page tables before memblock is ready.
That's needed to use early_ioremap() early and to use standard
page mappings with fixmap.

Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
 arch/powerpc/include/asm/fixmap.h |  4 ++++
 arch/powerpc/kernel/setup_32.c    |  2 +-
 arch/powerpc/mm/pgtable_32.c      | 16 ++++++++++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/fixmap.h 
b/arch/powerpc/include/asm/fixmap.h
index 2ef155a3c821..ccbe2e83c950 100644
--- a/arch/powerpc/include/asm/fixmap.h
+++ b/arch/powerpc/include/asm/fixmap.h
@@ -86,6 +86,10 @@ enum fixed_addresses {
 #define __FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
 #define FIXADDR_START          (FIXADDR_TOP - __FIXADDR_SIZE)
 
+#define FIXMAP_ALIGNED_SIZE    (ALIGN(FIXADDR_TOP, PGDIR_SIZE) - \
+                                ALIGN_DOWN(FIXADDR_START, PGDIR_SIZE))
+#define FIXMAP_PTE_SIZE        (FIXMAP_ALIGNED_SIZE / PGDIR_SIZE * 
PTE_TABLE_SIZE)
+
 #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NCG
 #define FIXMAP_PAGE_IO PAGE_KERNEL_NCG
 
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 15f0a7c84944..d642e42eabb1 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -80,7 +80,7 @@ notrace void __init machine_init(u64 dt_ptr)
        /* Configure static keys first, now that we're relocated. */
        setup_feature_keys();
 
-       early_ioremap_setup();
+       early_ioremap_init();
 
        /* Enable early debugging if any specified (see udbg.h) */
        udbg_early_init();
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index f62de06e3d07..9934659cb871 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -29,11 +29,27 @@
 #include <asm/fixmap.h>
 #include <asm/setup.h>
 #include <asm/sections.h>
+#include <asm/early_ioremap.h>
 
 #include <mm/mmu_decl.h>
 
 extern char etext[], _stext[], _sinittext[], _einittext[];
 
+static u8 early_fixmap_pagetable[FIXMAP_PTE_SIZE] __page_aligned_data;
+
+notrace void __init early_ioremap_init(void)
+{
+       unsigned long addr = ALIGN_DOWN(FIXADDR_START, PGDIR_SIZE);
+       pte_t *ptep = (pte_t *)early_fixmap_pagetable;
+       pmd_t *pmdp = pmd_ptr_k(addr);
+
+       for (; (s32)(FIXADDR_TOP - addr) > 0;
+            addr += PGDIR_SIZE, ptep += PTRS_PER_PTE, pmdp++)
+               pmd_populate_kernel(&init_mm, pmdp, ptep);
+
+       early_ioremap_setup();
+}
+
 static void __init *early_alloc_pgtable(unsigned long size)
 {
        void *ptr = memblock_alloc(size, size);
-- 
2.25.0